usb: typec: tcpci: use GENMASK() for TCPC_CC_STATUS_CC[12]

usb: typec: tcpci: use GENMASK() for TCPC_CC_STATUS_CC[12]

The existing code here, particularly in maxim_contaminant.c, is
arguably quite hard to read due to the open-coded masking and shifting
spanning multiple lines.

Use GENMASK() and FIELD_GET() instead, which arguably make the code
much easier to follow.

While at it, use the symbolic name TCPC_CC_STATE_SRC_OPEN for one
instance of open-coded 0x0.

Signed-off-by: André Draszik <andre.draszik@linaro.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20240710-tcpc-cleanup-v1-3-0ec1f41f4263@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>